The invention relates to standardized, primary osteoblast cell cultures from test persons with suspected osteoporosis, examined using differential diagnosis, their use in osteoporosis diagnostics, and in testing potential therapeutic agents for osteoporosis, and a method for diagnosing osteoporosis permitting a 95% reliable statement as to the presence of osteoporosis, and a method for testing potential osteoporosis therapeutic agents, by which an effective osteoporosis therapeutic agent can be determined for each individual case.
Osteoporosis (bone atrophy) is a severe systemic disease of the skeleton, which is characterized by a reduced bone density (mass) occurring with a mosaic-like pattern and micro-structural changes in the bone tissue. The bone tissue of a healthy adult person is subject to continuous formation and degradation even after completed development. Normally, two opposing processes are balanced. In the event of a prevailing degradation phase (bone resorption), however, the initial result will be bone atrophy (osteoporosis), i.e., reduced bone stability. The disease is accompanied by mostly lifelong pain, more frequent fractures, which may be followed by complications up to a fatal course. It is estimated that more than 200 million people worldwide, 7-8 millions in Germany, suffer from the above disease.
Therapeutic agents currently used against osteoporosis, such as estrogens, progesterones, calcitonin, di/bisphosphonates and calcium are merely capable of slowing down or reducing bone atrophy as a result of their effectiveness as anti-bone resorbers. Using the above, there is no success in replacing bone substance which has already been lost.
The effects of the following factors on bone growth are currently investigated: Parathyroid hormone (PTH) and derivatives thereof, vitamin D3, anabolic steroids, fluorides, insulin-like growth factors I and II, prostaglandins and growth hormone (GH). The results of clinical studies published up to now are far from sufficient because the increase in bone density with most factors is only 1-3% per 1-3 years (clinical symptoms of osteoporosis frequently appear only after 50% of the bone mass has been lost) and frequently, the fracture rates are not reduced. Thus, in order to be capable of counteracting massive progress of this disease, early recognition of osteoporosis and generally, diagnosis of osteoporosis play an important role.
Currently used physical diagnostic methods such as single photon absorptiometry (SPA), single and dual X-ray absorptiometry (SXA; DXA) and quantitative computed tomography (QCT) are costly; they are available at major clinical centers only and extremely difficult to interpret. Ultrasound examinations and X-ray photodensitometry are low-cost methods but involve similar drawbacks.
The currently used classical biochemical methods for diagnosing osteoporosis are based on the determination of hydroxyproline in urine, calcium excretion, alkaline phosphatase and osteocalcin in serum. The determination of these parameters in serum is non-specific because the values measured are highly variable.
New methods for estimating the bone resorption, such as the measurement of deoxypyridinoline in urine, or methods for determining the bone formation, such as the measurement of bone-specific alkaline phosphatase and procollagen peptides in serum should provide more information.
However, all the above-mentioned methods are disadvantageous in that they provide indications not before part of the bone mass has already been lost.
It was therefore the object of the invention to provide a low-cost method for diagnosing osteoporosis, which is easy to handle for a person skilled in the art and provides in each individual case an at least 95% reliable classification into groups of persons suffering from osteoporosis and those not suffering from osteoporosis or with respect to therapeutic success by unequivocally interpretable and reproducible parameters.
The object of the invention is accomplished in that for the first time, standardized osteoblast cell cultures from osteoporotic patients are established according to claim 1, which are viable for months and excellently useful in diagnosing osteoporosis.
It was found that osteoblast cells according to the invention obtained from osteoporotic patients exhibit pathological changes in their proliferation and differentiation when compared to osteoblast cells from non-osteoporotic patients. Using discriminant analysis, the data concerning proliferation rate and expression intensity of osteoblast-specific differentiation markers are assigned to osteoporotic and non-osteoporotic patients with an accuracy of more than 95%, where persons suffering from osteoporosis and those not suffering from osteoporosis exhibit highly significant differences.
Surprisingly, these cell cultures are also excellently suited for testing potential osteoporosis therapeutic agents, thereby permitting an individually effective therapeutic agent to be determined for each patient.